A useful article to read if you wish to know the nitty-gritty details of how macro renaming works. This may help you to not only understand syntax-rules better, but will also provide a good basis for grokking explicit renaming and other macro systems.

An excellent post by Alex Shinn, explaining different macro systems. Please note: This was written when CHICKEN 4 was not yet released, and hence refers to various different macro systems available for CHICKEN at the time. This is no longer true since CHICKEN now has ER- and IR-macros built in.